Nobody said you were entitled to a victory on the night when J.R. Smith decides to bring along his private tornado, the night you hold an efficient offensive team to 11 under its average, the night you go punch-for-punch with arguably the best backcourt in the East.

Nobody said Washington was going to roll over, either: The Wizards want this as badly as the Knicks, and they’re hardly satisfied with sixth place as they pursue their first playoff berth in six years. You think the Knicks know hunger, after being irrelevant for so long? Since 1982, the Wizards have won exactly one playoff series — that one coming under Eddie Jordan, nine years ago.

And nobody said there wasn’t another thunderbolt left on the calendar.

It’s just that the Knicks played with a playoff-level intensity Friday night, only to fall one point short because Carmelo Anthony’s right shoulder was screaming for an early vacation.

As it turns out, it just might get one, because this 90-89 gut punch they took from Washington at the Garden could choke whatever breath is left in this season.

"A tough loss, man," Melo said, after an agonizing performance that included 10 points and nine turnovers. "I wish I coulda done better, played better. I thought my teammates did what they had to do — J.R. had a phenomenal game, so I just wish I could have rewarded that."

It doesn’t get much more agonizing than this, not when you factor in Atlanta’s rout of Cleveland, which gives the Hawks (33-42) a one-game lead on the Knicks (33-44) in the jostle for eighth place in the East.

And certainly not when you factor in J.R.’s extraordinary show, which included 32 points on 12-for-23 shooting (8-for-16 from the outback), and the kind of tap-to-buzzer effort that inspired the entire building.

Admittedly, we had ignored the warning signs. He had played superbly against the Nets and Wednesday was no fluke. The line from Phil Jackson on Thursday — about how the Knicks can be a tough out in the playoffs "with J.R. playing at the level he’s playing at now, yes" — was more than a pipe dream. And Mike Woodson’s pregame assertion that J.R. was "back playing at that level that got him the Sixth Man award last season" suddenly didn’t sound like ordinary coach-speak.

So he backed it all up Friday night, matching John Wall and Bradley Beal play for play, even if the Wiz backcourt combo had 47 points combined.

It just didn’t get the Knicks to the finish line.

Because he had virtually no offensive help, with Melo in a 5-for-14 ditch. He never even got to the line.

"I knew it was bothering him," Woodson said, "but you know, we’ve got to have Melo on the floor."

"There’s a dogfight we’re in," Melo said. "There was no way I was coming out."

Good in theory.

In practice, not so much. Woody was left with two bad choices, and he nearly got away with it.

The Knicks trailed 83-82 when they got four straight stops — they even forced three turnovers — before a pair of free throws from Raymond Felton got them the lead as the clock slipped under two minutes.

Then J.R. relapsed into the old J.R.

Indeed, the offense was already in the tank, so Smith forced a 21-foot leaner that bounced long, giving the Wiz a transition opportunity, with Wall pitching it ahead to Beal. J.R. tried to run him down — which is probably impossible, for a non-equine — and fouled him as Beal slammed home a dunk to give Washington a lead. The free throw bumped it to 86-84.

At 88-86, Melo made a lazy crosscourt pass with 55 seconds left that was picked off — his ninth turnover — and the Wiz could have sealed it there. But Wall returned the favor with a bad pass, and Melo made amends by drawing a triple team and finding Felton for a corner 3 that gave the Knicks an 89-88 lead with 33.5 ticks left.

Good vibes all around — until Beal found a shooter’s pocket behind Marcin Gortat’s screen to get the lead back for Washington at 22.9.

So on the Knicks’ last gasp, Melo got a high screen, took his dribble into the paint, and had the ball poked away on a drive. It ended up in J.R.’s hands, but his 26-footer was wide left at the horn.

So close, yet so far.

And it will be disappear entirely, perhaps, if the Knicks don’t win at Miami Sunday, because Atlanta owns the tie-breaker. Either way, they’re bringing a one-armed forward.

"As of right now, for sure, I’ll be there," Anthony said.

Again, it hardly seems fair. But given what the Knicks have been through this year, it has a ring of symmetry to it.